1. Field of the Invention
The present invention relates to a generated voltage reference that can selectively track with variations in temperature or be process, voltage and temperature (PVT) independent.
2. Description of the Prior Art
Many circuits use voltage references to generate outputs that are a fraction of the input but follow the input's characteristics. These generated references can then be input to another system.
A typical circuit for generating a reference voltage takes a PVT independent reference, and generates a PVT independent output. Please refer to FIG. 1. FIG. 1 is a diagram of a reference voltage generation circuit 100 according to the prior art. The circuit comprises a comparator 150, having a PVT independent reference as a first input, and feedback from the output as the second input. The output is further coupled to a first resistor R1 and a second resistor R2 which are coupled in series, the second resistor R2 being coupled to ground. The second resistor R2 is a variable resistor, for varying the point at which the output is generated. This output will also be PVT independent. Once the resistance of the second resistor R2 is set, the generated output voltage will remain constant.
For some circuits, however, it is impractical to operate over all temperature conditions. For example, at low temperatures, circuit components will have a performance problem. At high temperatures, the problem of leakage current occurs. It is therefore advantageous to provide a reference voltage generation circuit that can provide an output that has some dependency on temperature variations.